This invention relates to a contact lens article made of a silicon- and fluorine-containing resin. More particularly, it relates to a contact lens article having superior oxygen permeability and shape stability.
Among the contact lenses now in extensive use, there are known an oxygen-permeable hard contact lens and a water-containing soft contact lens. The water-containing soft contact lens is excellent in wearing feeling, but insufficient in oxygen permeability of the lens material. While it may be contemplated to elevate water content in the lens material to improve its oxygen permeability, reports of clinical data demonstrate that the lens is apt to be contaminated by miscellaneous bacteria and serious complications may be brought about to cornea and conjunctiva. Conversely, the oxygen-permeable hard contact lens is enjoying high evaluation with respect to high oxygen permeability, astigmatism-curative effects, durability and safety, and is becoming a prevalent contact lens. In keeping therewith, researches are being made extensively in the field of oxygen-permeable hard contact lens. However, in these researches of the oxygen-permeable contact lens, the main concern is its oxygen-permeability, while the other properties required of the contact lens have not been taken account of sufficiently.
For example, the contact lenses described in Japanese Patent Publication No. 8769/1987 and Japanese Patent Publications Nos. 61928/1987 and 36646/1988 are excellent in oxygen permeability, but are unsatisfactory in shape stability and resistance to contamination. Dialkyl fumarate, employed in Japanese Laid-open Patent Applications Nos. 99720/1987 and 212618/1987, has only low copolymerizability and, even supposing that it is copolymerized in some way or other, it is so brittle that it can be cracked or broken very easily, causing dangers to the user. On the other hand, the contact lens shown in Japanese Laid-open Patent Application No. 176909/1986 is low in oxygen permeability so as to be unsuitable for continuous wearing to which particular attention has been directed in recent years.